Tongue assembly for use in a seat belt device

ABSTRACT

A tongue assembly for use in a seat belt device is formed of a tongue main body engaging a buckle and a slider slidably disposed over the main body. A first slit is situated in a middle portion of the main body to extend in a direction perpendicular to an inserting direction of the main body relative to the buckle. A first wall portion is fixed to the main body to project upwardly from an upper surface of the main body along the first slit at a side of a rear portion. A second wall portion is formed in an upper side of the slider and has a surface opposing to the first wall portion. A second slit is formed at a lower side of the slider so that a rear edge of the second slit at a side of a rear portion of the main body is situated close to an insertion portion of the main body with respect to the surface of the second wall. A third slit is further formed in the rear portion of the main body. A seat belt extends between the first and second wall portions, through the first and second slits, under the lower side of the slider and through the third slit so that when a tension is applied from the side of the third slit, the slider is pulled toward the rear portion of the main body to urge the second wall portion of the slider to the first wall portion to thereby strongly hold the seat belt between the first and second wall portions.

FIELD OF THE INVENTION

The present invention relates to a tongue assembly to which a seat beltis engaged and, more in particular, it relates to a tongue assemblysuitable to a case in which a child seat is secured to a vehicle seat bymeans of a belt.

DESCRIPTION OF THE RELATED ART

As is well-known, a seat belt device is disposed to a vehicle and it hasa function of holding and protecting an occupant on a seat uponcollision of the vehicle.

As one of such seat belt devices, there has been known a three-pointseat belt device as shown in FIG. 11, in which a tongue 12 is put over abelt 10, the top end of which is secured to a vehicle body while therear end of which is wound around a seat belt retractor (notillustrated), and the tongue 12 is inserted into a buckle 14 secured tothe vehicle body.

A child seat (seat set for infant) 18 placed on a seat 16 is sometimessecured to the seat 16 as shown in FIG. 11 by using the belt 10 of thethree-point seat belt device (for example as disclosed in JapaneseUtility Model Publication Hei 2-35012). In the drawing, 10A denotes aportion of the belt 10 situated on the side of the top end from thetongue 12 (lap belt), and the child seat 18 is constrained by theportion 10A. 10B denotes a portion situated on the side of the retractorfrom the tongue 12 (shoulder belt).

In such a child seat fixing structure, it is necessary that the lap belt10A is always stretched under a sufficient tension to firmly secure andhold the child seat 18 to the seat 16 even when the shoulder belt 10B ofthe tongue 12 on the side of the retractor slackens.

In Japanese Utility Model Publication Hei 2-35012, the belts 10A and 10Bare overlaid at the portion of the tongue 12, so that the tension of thebelt 10A on the side of the top end is maintained by friction betweenboth of them.

As a seat belt device capable of maintaining the tension of the lap belt10A, U.S. Pat. Nos. 4,480,854, 4,588,207 and 4,903,377 disclose astructure as shown in FIGS. 9 and 10, in which a slider 22 is fit over atongue main body 20, the slider 22 is resiliently biased backward to thetongue by the tension applied to the belt 10 so as to put the belt 10between a wall 24 disposed to the tongue main body 20 and a rear edge 26of the slider 22.

The above-mentioned constitution in the prior art involves a problemthat the belt slips, failing to maintain a sufficiently high tension tothe top end side 10A of the belt.

OBJECT AND SUMMARY OF THE INVENTION

An object of the present invention is to provide a tongue assemblycapable of firmly holding a lap belt.

In the first aspect of the present invention, a tongue assembly for usein a seat belt device comprises a plate-like tongue main body having afront edge defined as a portion to be inserted into a buckle and a firstslit disposed therebehind for the insertion of a belt and extendedlaterally crossing the longitudinal direction, a slider having a flatframe shape surrounding a portion of the tongue main body situatedbehind the insertion portion and fitted over that tongue main bodyretractably in the longitudinal direction, a first wall portion raisedfrom one of plate surfaces of the tongue main body at the rear edge ofthe first slit of the tongue main body, a second wall portion disposedto oppose to the first wall portion at a rear edge of portion of theslider that opposes to the one of the plate surfaces of the tongue mainbody and capable of seizing a belt with respect to the first wallportion, a second slit for insertion of the belt extended in the lateraldirection at a position overlapping the first slit in a portion of theslider that opposes to the other of the plate surfaces of the tonguemain body, in which the rear edge of the second slit situates ahead ofthe rear edge of the first slit even when the first wall portion and thesecond wall portion are overlapped while seizing the belt therebetween,a third slit extended laterally behind the first slit of the tongue mainbody, in which the third slit situates behind the rear edge of theslider even when the first wall retracts to a retracting limit.

A tongue assembly for use in a seat belt device in the second aspect ofthe present invention is as defined in the first aspect, in which arecess is disposed to the tongue main body for communicating the thirdslit and the rear edge of the tongue main body.

In the tongue assembly for use in the seat belt device according to thepresent invention, the shoulder belt is inserted from one of the platesurfaces into a portion between the first wall of the tongue main bodyand the second wall of the slider rear edge and, further, inserted intothe first slit of the tongue main body. Further, it is passed throughthe second slit of the slider and turned to the rearward of the tongueassembly, and pulled out from the third slit to the side of one of theplate surfaces to form a lap belt.

In the constitution as described above, when a tension is applied to thebelt, the slider is pushed to the backward of the tongue assembly by thetension and the belt is put between the first and the second wallportions.

In the present invention, the lap belt is turned to the backward fromthe second slit to the third slit. Accordingly, since the force exertedon the slider by the tension applied to the lap belt substantiallydirects just behind, the slider is resiliently biased backward extremelystrongly. Accordingly, it is held between the first and the second wallportions strongly. Therefore, even when the shoulder belt slackens, anextremely high tension remains in the lap belt. That is, even if theshoulder belt slackens, the lap belt is kept to continuously hold thechild seat strongly.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a vertical cross sectional view in a state in which a belt ispassed through a tongue assembly in an embodiment according to thepresent invention;

FIG. 2 is a vertical cross sectional view of the tongue assembly in astate in which the belt is removed;

FIG. 3 is a perspective view of a tongue assembly in a state in whichthe belt is passed;

FIG. 4 is a perspective view of a tongue assembly in which the belt isremoved;

FIG. 5 is a perspective view for the bottom of the tongue assembly in astate where the belt is removed;

FIG. 6 is a plan view of a tongue assembly;

FIG. 7 is a bottom view of a tongue assembly;

FIG. 8 is a cross sectional view of a tongue assembly in a case wherethe way of passing the belt is made different;

FIG. 9 is a cross sectional view of an existent tongue assembly;

FIG. 10 is an exploded perspective view of the existent tongue assembly;and

FIG. 11 is a perspective view illustrating a fixing structure for achild seat.

PREFERRED EMBODIMENTS

Description will now be made to preferred embodiments of the presentinvention with reference to FIGS. 1 through 7.

A plate-like tongue main body 30 comprises a metal plate 32 and asynthetic resin portion 34 secured to the metal plate 32. The metalplate 32 and the synthetic resin portion 34 are integrated by insertmolding.

The front end of the metal plate 32 constitutes an insertion portion 36into a buckle not illustrated and the insertion portion 36 has anopening 38 perforated therein for engagement with an engaging member ofthe buckle.

A first slit 40 is perforated at the rear end of the tongue main body 30and a first wall 42 is formed from the rear edge of the slit 40 so as toprotrude at one side (upper surface in FIG. 1) of the tongue main body.

Further behind the first slit 40, a third slit 44 is perforated toextend in a lateral direction crossing the longitudinal direction of thetongue main body 30. A recess 46 is formed so as to communicate thelongitudinal middle portion of the third slit 44 with the rear edge ofthe tongue main body 30, so that a belt 10 can be inserted through therecess 46 into the third slit 44.

A flat frame-shaped slider 48 is fit movably over the tongue main body30 in the longitudinal direction. The slider 48 has a second slit 50 anda second wall 52. The second wall 52 is formed to the rear edge of theslider 48 on one side of the plate surfaces of the tongue main body 30and opposes to the first wall 42.

The second slit 50 is extended in the other of the plate surfaces (lowersurface in FIGS. 1, 2) of the tongue main body 30 in the lateraldirection crossing the longitudinal direction of the tongue main body30. The rear edge 50A of the second slit 50 situates ahead of the firstwall 42 (rightward in FIGS. 1, 2) also in a state where the second wall52 overlaps with the first wall 42 by way of the belt 10.

Further, the third slit 44 is disposed so as to situate behind the rearedge of the slider 48 also in a state where the slider 48 is retractedto the retracting limit so as to put the belt 10 between the first wall42 and the second wall 52.

In the tongue assembly having thus been constituted, the shoulder belt10B of the belt 10 reaches the first slit 40 while passing between thefirst wall 42 and the second wall 52 and further passes through thefirst slit 40 and passes through the second slit 50. Further, the belt10B is turned back at the rear edge of the 50A of the second slit 50 andreaches the third slit 44 and then passes through the third slit 44 andreaches the belt top end. A belt situated on the side of the top endfrom the turned back portion at the tongue main body 30 constitutes alap belt 10A.

When tension is applied to the belt 10, the belt 10 resiliently biasesthe slider 48 to the backward of the tongue as shown by arrow A in FIG.1, in which the belt is strongly held between the second wall 52 and thefirst wall 42.

As apparent from FIG. 1, in this embodiment, the lap belt 10A turnedback at the rear edge 50A of the second slit 50 is extended straightforward along the slider 48 behind the tongue. Accordingly, the tensionapplied to the belt 10 strongly attracts the slider 48 to the backwardof the tongue, and the belt is firmly held between the first and thesecond walls 42 and 52. In addition, since the belt 10 is strongly heldbetween the first wall 42 and the second wall 52, if the shoulder belt10B slackens, the tension is maintained as it is on the side of the lapbelt 10A from the walls 42, 52, and the slider 48 maintains a stronglybiased state in the direction of an arrow A. Accordingly, even if theshoulder belt 10B slackens, a large tension remains in the lap belt 10A,thereby making it possible to firmly hold the child seat on the vehicleseat continuously by the lap belt 10A.

In the tongue assembly according to the present invention, the belt 10is inserted and passed through as shown in FIGS. 1 and 3. On thecontrary, if the belt is inserted and passed through as shown in FIG. 8,no sufficient tension remains in the lap belt 10A, failing to hold thechild seat firmly to the vehicle seat.

The reason is though such that the lap belt 10A, after passing throughthe rear edge 50A of the second slit 50, does not extend backwardly asit is and, accordingly, the component of the force applied to the slider48 in the direction of the arrow A is reduced, thereby decreasing theseizing force for the belt 10 between the first wall 42 and the secondwall 52.

As has been described above, with a tongue assembly for use in the seatbelt device according to the present invention, the child seat of thevehicle seat can be held strongly and, even if the shoulder beltslackens in this case, the child seat can be continuously held firmly bythe lap belt.

In the tongue assembly of the present invention, the belt can beinserted much easily to the third slit.

What is claimed is:
 1. A tongue assembly for use in a seat belt deviceadapted to be attached to a seat belt and to engage a buckle,comprising:a tongue main body having a rear portion, an insertionportion at a side opposite to the rear portion and adapted to engage thebuckle, a middle portion between the rear portion and the insertionportion, and upper and lower surfaces, a first slit situated in themiddle portion of the main body and extending in a directionperpendicular to an inserting direction of the main body relative to thebuckle, a first wall portion fixed to the main body, said first wallportion projecting upwardly from the upper surface of the main body andextending along the first slit at a side of the rear portion, a sliderslidably disposed over the middle portion of the main body and havingupper and lower sides, a second wall portion formed in the upper side ofthe slider, said second wall portion extending parallel to the firstslit at a side of the insertion portion and having a surface opposing tothe first wall portion, a second slit formed at the lower side of theslider, said second slit extending parallel to the first slit anddisposed under the second wall portion so that a rear edge of the secondslit at a side of the rear portion of the main body is situated close tothe insertion portion of the main body with respect to the surface ofthe second wall, and a third slit formed in the rear portion of the mainbody and extending parallel to the first slit, said seat belt extendingbetween the first and second wall portions, through the first and secondslits, under the lower side of the slider and through the third slit sothat when a tension is applied from the side of the third slit, theslider is pulled toward the rear portion of the main body to urge thesecond wall portion of the slider to the first wall portion to therebystrongly hold the seat belt between the first and second wall portions.2. A tongue assembly according to claim 1, wherein said tongue main bodyincludes a recess at the third slit to communicate the third slit withan outside of the main body.
 3. A tongue assembly according to claim 1,wherein said seat belt includes a lap belt and a shoulder belt, saidshoulder belt extending from the first slit and the lap belt extendingfrom the third slit.
 4. A tongue assembly according to claim 3, whereinthe second slit is positioned relative to the first wall portion suchthat when the lap belt is pulled, the rear edge of the second slit ismoved toward the rear portion of the main body to firmly hold the seatbelt between the first and second wall portions.
 5. A tongue assemblyaccording to claim 4, wherein the second wall portion extends downwardlyfrom the slider and located inside the first slit.
 6. A combination of atongue assembly and a seat belt for use in a seat belt device adapted toengage a buckle, comprising:said tongue assembly including: a tonguemain body having a rear portion, an insertion portion at a side oppositeto the rear portion and adapted to engage the buckle, a middle portionbetween the rear portion and the insertion portion, and upper and lowersurfaces, a first slit situated in the middle portion of the main bodyand extending in a direction perpendicular to an inserting direction ofthe main body relative to the buckle, a first wall portion fixed to themain body, said first wall portion projecting upwardly from the uppersurface of the main body and extending along the first slit at a side ofthe rear portion, a slider slidably disposed over the middle portion ofthe main body and having upper and lower sides, a second wall portionformed in the upper side of the slider, said second wall portionextending parallel to the first slit at a side of the insertion portionand having a surface opposing to the first wall portion, a second slitformed at the lower side of the slider, said second slit extendingparallel to the first slit and disposed under the second wall portion sothat a rear edge of the second slit at a side of the rear portion of themain body is situated close to the insertion portion of the main bodywith respect to the surface of the second wall, and a third slit formedin the rear portion of the main body and extending parallel to the firstslit, said seat belt extending between the first and second wallportions, through the first and second slits, under the lower side ofthe slider and through the third slit so that when a tension is appliedfrom the side of the third slit, the slider is pulled toward the rearportion of the main body to urge the second wall portion of the sliderto the first wall portion to thereby strongly hold the seat belt betweenthe first and second wall portions.
 7. A combination according to claim6, wherein said seat belt includes a lap belt and a shoulder belt, saidshoulder belt extending from the first slit and the lap belt extendingfrom the third slit.